hi @Jason Parker ,
I think you don't post in the right category, there is a difference between Microsoft 365 and Windows 365.
You can see Windows 365 as a Cloud PC ( So all the Windows (Operating System) are hosted in the Cloud ).
With Microsoft 365, you have differents products like Teams, Exchange Online ... Depends of the M365 type of licence.
But for a begining of response, multiple users with different m365 licence can communicate together
M365 Business Basic licence users and M365 Business standard users, can communicate, ( If all users are in the same orgamization, its more than easy).
No problem with that.
Hope it help
Have a great day